How often do you change your plugs?

I took a road trip this weekend and noticed that after the JEEP had been run for about 2 1/2 hours it would seem to skip right around 60mph. A little less, no skip, a little more, no skip, and it was intermittent. It did something like this summer, but it was at 40, then 50, then 60mph. That time it was the brake pedal sensor that was bad and the mech. said that the computer thought I was putting on the brakes when I really wasn't, causing me to get a "downshift" effect. I've got about 23-24000 miles on my plugs, wires, dist cap and rotor. Seems to soon to change my plugs, but could it be a bad one that acts up when the engine is good and hot? Sorry for the ramble...
Thanks in advance

I use Autolite Platinum, and change them every alternate year. I have a convenient reminder to do so - the letter from the Smog Nazis!

I find that a two-year interval for changing plugs usually works out nicely.

5-90

I guess I should do mine, been about 6 years and 150K miles.

Owner's manual says every 30,000 miles. With national average driving being ~15000/yr that works out to ~ 2 yrs.

Generally every other spring/summer I do plugs, cap, rotor, wires, all dealer supplied OEM parts, at 240,000+ mi it has worked for me... Our two TJ's are now on the same schedule.... I do about 40,000 a year now that I no longer commute to NJ...

hmmm I recon its time to change mine then with the original plugs and 107k- I did pull em the other week and they look new... can older plugs cause hesitation??

I guess its overkill, but I change my plugs and wires at least once per year. Sometimes twice if the winter has been really wet. I've only changed the dist and rotor twice in the past 4 years though.

Beej said:

I guess its overkill, but I change my plugs and wires at least once per year. Sometimes twice if the winter has been really wet. I've only changed the dist and rotor twice in the past 4 years though.

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The cap and rotor get the most wear, physical wear that is. When I do my factory OEM plugs they are usually in good shape but are around .050-.055 gap after 50K or so, the cap contact points generally have tracks worn in them. I also use dielectric grease on both ends of the plug wires, makes em easier to get off though I still end up leaving some skin and blood when removing the #1 plug wire....

just check the gap and be liberal with the use of di-electric grease when you put the new ones on. I have found the Motocraft plugs to last the longest in all vehicles. I know - ford plugs, but they make them for all vehicles... and last well.

be careful with the wires, its easy to break them - epecialy if they arent new.

Wish people would specify the year of their XJ and the amount of miles, problems like this can be year/mileage dependent.

IF YOU have a 87-90 XJ, it has an EGR valve. Over time it gets carboned up and will stick. When it finally moves you get a hickup like you described. I took mine into the dealer and the mechanic found the bad EGR and replaced it. That fixed the problem for my 88 XJ

I just did it on a 99 with 79k miles that I just picked up.

It looked as though it had never been done; cap, rotor and plugs were very worn.

As others have said, 2 years is probably a good rule of thumb.

RichP said:

The cap and rotor get the most wear, physical wear that is. When I do my factory OEM plugs they are usually in good shape but are around .050-.055 gap after 50K or so, the cap contact points generally have tracks worn in them. I also use dielectric grease on both ends of the plug wires, makes em easier to get off though I still end up leaving some skin and blood when removing the #1 plug wire....

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I´m with Rich, my cap and rotor seem to wear about twice as fast as my plugs. I´ve often changed plugs that were still good. Cap seems to be an almost yearly replacement. Though mine may be worse, I get things wet a lot and they salt the roads around here.
Many times (most) when I get a miss at idle it´s the cap and rotor. Rotor to electrode gap really grows, electrodes burn, green stuff grows in there and there is often a coating of carbon powder from the wear of the contact pin between the cap and rotor.
A budget tune up, clean the buildup off of the elctrodes in the cap and rotor tip, wipe out the distributor cap plastic to remove the carbon dust. And check/clean the spark pluig cable end contacts at the distributor cap. Almost always helps mine, run better.